This invention relates to devices for measuring the weights of objects as well as for measuring the first moment of objects about a fixed fulcrum point and, more particularly, to a device for measuring the total weight, swing weight, and weight of components of a golf club.
The game of golf is extremely popular throughout the entire world, and both the amateur and the professional golfer seek every refinement and advantage possible. A set of golf clubs includes numerous attributes which may be adjusted, such as golf club length, golf club weight, shaft weight and flex, grip size, weight and texture, club head size, weight, shape, lie and loft angle, etc. All of these factors are known to affect the golf club mass distribution, its moment of inertia, feel, and level of playability.
The mass distribution, moment of inertia, and xe2x80x9cfeelxe2x80x9d of a golf club are usually defined by a single attribute, referred to in the trade as swing weight. Swing weight is the first moment or couple of the golf club and is the product of the distance from the grip cap of the golf club (the extreme end opposite the club head) to a fixed fulcrum point, usually fourteen or twelve inches away from the grip cap. Swing weight is the amount of counterbalancing weight needed to counteract that moment in order for the golf club to balance on the fulcrum point. For example, a golf club having most of its mass concentrated toward the club head will have a higher swing weight than a golf club having most of its mass concentrated toward the upper end of the shaft and grip.
Just as the most desirable weight of a golf club will fall within a maximum and minimum limit and will vary according to the specific need of the golfer using the club, so will the swing weight vary between a maximum and a minimum limit and will vary according to the specific preferences of the golfer using the clubs. For example, a golf club having more of the mass concentrated toward the grip will have a relatively lower moment of inertia in the swing, and thus will impart less driving force to the ball, while a golf club having more mass concentrated toward the club head will have a higher moment of inertia which may make the club more difficult to swing with sufficient velocity for optimum driving distance. Thus, there is an optimum swing weight for every golfer. Moreover, swing weights should preferably be matched in a set of golf clubs so the golfer need not change his or her swing for different clubs having different swing weights.
Accordingly, golf club manufacturers attempt to measure and adjust the swing weights of their sets of golf clubs precisely in order to match the swing weights of each of the golf clubs as closely as possible. However, swing weight adjustment is a tedious and time consuming operation. Each time the swing weight is adjusted, each component of a golf club set must first be weighed in order to match the weights as closely as possible to the desired total weight and swing weight range. Then, the components must be assembled to build the new golf club. The assembled golf club must be weighed again, the swing weight measured and, if necessary, adjusted to the final desired swing weight and the total weight specifications by adding or removing weights, when possible, to the various components, such as the shaft grip and head.
Scales and balances used for measuring golf club weight and swing weight are typically unequal arm mechanical units, using a relatively small balance weight, i.e., counterpoise, adjusted along a relatively long arm from a pivot at a fulcrum point, to provide sufficient moment to counterbalance the weight of the golf club component being weighed on a relatively short arm from the fulcrum point. Devices of this type having sufficient accuracy typically have a relatively long counterpoise arm, resulting in a relatively fast oscillation period and poor damping characteristics. The delay in balancing due to the oscillation makes balancing a golf club rapidly and efficiently very difficult. However, reducing the length of the counterpoise arm to reduce the relatively long oscillation time and amplitude adversely affects the accuracy of the balancing instrument. Furthermore, it is usually difficult to determine with certainty when the scale has reached a position of equilibrium. Usually, the level, i.e., balance, indicator is at one end of the balance, a considerable distance from the fulcrum point. Finally, the fulcrum point is usually supported at the front and rear of the arm of the balance. This structure makes sliding of the counterpoise past the fulcrum point in a single motion impossible. In addition, reading of the indicia on the arm at or near the fulcrum point is difficult, if not impossible.
The present invention provides for ameliorating these disadvantages of the prior art. The advantages of the present invention will be apparent from the description as set forth below.
A golf club swing weight balance and scale according to the invention includes a weighing beam having and extending between first and second ends, a grip backstop disposed at the second end of the weighing beam and including a grip cap compensator movable within the grip backstop between an extended position and a retracted position, a slide weight slideably mounted on the weighing beam, and a pivot assembly pivotally supporting the weighing beam at a location intermediate the first and second ends and including a single support member disposed on only one side of the weighing beam so that the slide weight can be moved from the first end to the second end in a single stroke.
In a golf club swing weight balance and scale according to the invention, the pivot assembly preferably comprises a knife edge fulcrum having first and second ends, one of the ends including a knife edge pivotally connected to the weighing beam.
The single support member preferably includes a stop arm extending across the weighing beam and limiting amplitude of oscillation of the weighing beam.
In a preferred golf club swing weight balance and scale according to the invention, the slide weight indicator includes a balance indicator indicating when the weighing beam is balanced. Most preferably, the balance indicator is a bubble level mounted on the slide weight.
The grip cap compensator includes a head having a shape for engaging and supporting a grip end of a golf club shaft on which no grip is present. The head of the grip cap compensator is substantially co-planar with a grip contact surface of the grip backstop when the grip cap compensator is in the retracted position, so that a grip of a golf club may be placed in contact with the grip contact surface during a swing weight measurement. The head of the grip cap compensator protrudes from the grip cap contact surface of the grip backstop by a distance substantially equal to the thickness of an end of a golf club grip when the grip cap compensator is in the extended position so that the swing weight of a gripless golf club can be accurately determined.
The present invention provides several advantages over other golf club scales. The golf club scale in accordance with the present invention advantageously allows the swing weight and total weight of fully assembled and partially assembled golf clubs to be determined accurately using a single scale. The simplified design and minimal number of components advantageously reduces the cost associated with manufacturing the scale. The swing weight and total weight of a golf club can also be accurately determined prior to the final assembly of a golf club, e.g., present invention allows the swing weight and total weight of a golf club and/or golf club components to be determined more quickly and accurately than other scales. The point at which the weighing beam has reached equilibrium, e.g., is balanced, can be verified more quickly and more accurately than with prior art balances. The present golf club scale also allows total weight and swing weight readings to be made easily and accurately in all regions of the scale because the fulcrum point support does not obscure any part of the weighing beam indicia. Further, the support of the weighing beam permits movement of the counterpoise along the entire length of the weighing beam since the support does not obstruct the movement of the counterpoise at any point along the weighing beam.